There is no single genetic mechanism behind sex
differences in different species and the existence of two sexes
seems to have evolved
multiple times independently in different evolutionary
lineages. Other than the defining difference in the type of
gamete produced, differences between males and females in one
lineage cannot always be predicted by differences in another. The
concept is not limited to animals; egg cells are produced
by chytrids, diatoms, water molds
and land plants, among
others. In land plants, female and male designate not only the egg-
and sperm-producing organisms and structures, but also the
structures of the sporophytes that give rise to
male and female plants.

Etymology and usage

The word female comes from the Latin femella, the
diminutive form of femina, meaning "woman," which is not actually
related to the word "male." The word was probably originally
femella, meaning "young girl." In the late 14th century, the
English spelling was altered so that the word paralleled the
spelling of "male."

The word female is generally considered neutral
when used as an adjective; when used as a noun, it is often
regarded as derogatory. Female judge would be preferable to woman
judge; "This judge is a woman" would be preferable to "This judge
is a female." There are exceptions: League of Women Voters is a
name chosen by the mostly-female members of the League. The
American Heritage Dictionary and the Random
House Dictionary are not completely clear on this point, which
is a sensitive point: it is hard to find neutral terms for women
performing jobs once reserved for men, because these women
generally insist that they belong there; and many other
people—including some women—insist that they do not.

The phrase the female, in the sense of the female
sex or the class of all women, figures prominently in the first act
of Henry
V, in which Henry's bishops discuss with him the right of the
French King to his throne—and Henry's right to usurp it. They
conclude that the salic law cited
by the French is not really French, but German, and that Henry can
properly invade France, thus prolonging the Hundred
Years' War.

Mammalian female

The distinguishing characteristic of mammalian
species is the presence of mammary
glands. The mammary glands are modified sweat glands that
produce milk, which is used
to feed the young during the period of time shortly after birth.
Only mammals have the capacity to produce milk. The
presence of mammary glands is
most obvious on humans, due to the tendency of
the female human body to store large amounts of fatty tissue near
the nipples, resulting in prominent breasts, although today some
human females also surgically
augment their breast size. However, mammary glands are present
in all mammals, although they are vestigial
in the male of the species.

The mammalian female is characterized by having
two copies of the X chromosome
as opposed to the male which carries only one X and one smaller
Y
chromosome. To compensate for the difference in size, one of
the female's X chromosomes is randomly
inactivated in each cell. In birds, by contrast, it is the
female who is heterozygous and carries a
Z and a W chromosome whilst the male carries two Z
chromosomes.

Mammalian females are also unique in that they
all bear live young (with the rare exception of monotremes, which lay eggs).
However, there are non-mammalian animals (such as sharks) whose eggs hatch inside
their bodies, which gives the appearance that they bear live
young.

Symbol

A common symbol used to represent the female sex is
♀ (Unicode:
U+2640 Alt
codes: Alt+12), a circle with a small cross underneath. This
symbol also represents the planet Venus and is a
stylized representation of the goddess
Venus' hand mirror. According to Schott, "The most established
view" is that the male and female symbols "are derived from
contractions in Greek script of the Greek names of these planets,
namely Thouros (Mars) and Phosphoros (Venus). These derivations
have been traced by Renkama who illustrated how Greek letters can
be transformed into the graphic male and female symbols still
recognised today." Thouros was abbreviated by θρ, and Phosphoros by
Φκ, which were contracted into the modern symbols.

Sex determination

The sex of a particular organism may be
determined by a number of factors. These may be genetic or
environmental, or may naturally change during the course of an
organism's life. Although most species with male and female sexes
have individuals that are either male or female, hermaphroditic animals
have both male and female reproductive organs.

Environmental determination

Some species develop into one sex or the other
depending on local environmental conditions, e.g. many
crocodilians' sex is influenced by the temperature of their eggs.
Other species (such as the goby) are capable of transforming,
as adults, from one sex to the other in response to local
reproductive conditions (such as a shortage of males). In humans
and most mammals, sex is determined chromosomally -- a Y sperm will
produce a male offspring and an X sperm a female. However, "local"
(vaginal and uterine) conditions, and possible physical differences
between X and Y sperm, may cause a number of environmental factors
-- time in menstrual cycle, vaginal pH, location of initial
ejaculate within the vagina, sexual position, postcoital position,
etc. to favor the conception of one sex or the other; there is a
long folkloric tradition and limited statistical evidence for many
of these factors.

FEMALE SENSOLOGY: Female are attracted towards
male naturally. But they tend to change their choice with time,
specially, during adolescense period. If their boy friends are
intelligent, they generally don't leave them. This is judged by
their marks. Research shows the following:- i) If boys get above
95% in subjects like Science, Maths, girls generally don't leave
their love since they believe that the guys are very intelligent.
ii) If they score more than 85% in English, they believe that the
guys are very good communicators and can get a job at any place
over the globe.

With time, female's idea keep changing as even
they mature and now they get attracted to men with good,
respectable or high salaried jobs.

All the above details are applicable for almost
95% of the female population of the world. This psychology works
more in less developed countries like the South Asian countries and
in those of Africa.

Sources

Ayers, Donald M. English Words from Latin and Greek
Elements. Second Edition. 1986. University of Arizona Press. United
States.